When Stroke Affects the Brain Stem



The brain stem serves as a bridge in the nervous system. All the fibers that go from the body to the brain and vice versa go through the brain stem. It sits at the top of the spinal column in the center of the brain.

Dr. Richard Harvey

“The brain stem is tucked in between the two cerebral hemispheres and only the very bottom of it actually comes out from under the brain where you could see it,” said Richard Harvey, medical director of the Center for Stroke Rehabilitation at the Rehabilitation Institute of Chicago. “There’s a hole in the bottom of the cranium where the spinal cord comes out, but the brain stem itself is all contained within the cranium, between those two hemispheres.”

The brain stem comprises the midbrain (attached to the cerebellum), the pons and the medulla (aka the medulla oblongata, at the top of, and connecting with, the spinal cord). These are not separate structures but rather groups of cells that control various distinct functions. The brain stem handles basic functions like breathing, swallowing, heart rate, blood pressure, sleeping and vomiting. The brain stem does not play a part in higher cognitive functions. About 10 percent of all ischemic strokes occur in the brain stem.

The pons is about the size of your thumb; the midbrain is smaller; and the medulla is about the size of the little finger. “All in all, they’re not big structures, but they’re packed full of fibers so even small injuries can hit lots of fibers that are carrying multiple types of information to and from the brain,” Harvey said.

Each part of the brain stem has its own cranial nerves and its own blood supply. “Because its functions are so important, the part of the circulatory system supplying blood to the brain stem is complex and cannot be overtaken entirely by any single stroke,” said Alejandro Rabinstein, a neurologist at the Mayo Clinic in Rochester, Minnesota.

Dr. Alejandro Rabinstein

The brain stem is somewhat protected from clots that start in the heart or in the arteries in the neck (emboli), which are the most common cause of stroke. “One of the most common mechanisms of brain stem stroke is penetrating artery disease,” Rabinstein said. “This is the disease of the small blood vessels that branch from the major arteries and go into the depths of the tissue, in this case, in the brain stem.” These penetrating vessels are too narrow to receive emboli and because they form perpendicularly to their parent vessel, a travelling clot is less likely to take a path that flows into them. “However, brain stem involvement can occur as part of more extensive strokes caused by embolism.”

 

 

Stroke in the Midbrain

A stroke in one side of the midbrain can affect eye movement on the same side, causing the eye to move to the side uncontrollably and keeping it from being able to move up and down. It also can cause droopy eyelid on the same side as the stroke and body weakness on the opposite side.

“Those particular symptoms are called Weber’s Syndrome,” Harvey said. “Survivors with Weber’s have all their face and mouth movements and such. They can talk just fine.”

A stroke that affects both sides of the midbrain can have dire consequences. “Typically what happens to these people is, not only can they not move anything, but they are likely to be comatose,” Harvey said. “A stroke there affects the ability to focus attention, which is compromised because the midbrain feeds right into the main place in the brain in charge of where our attention to the space around us is. We’ve known this for years because when scientists slice just above the midbrain in animal models, the animal goes into a coma.”

Stroke in the Pons

A stroke on one side of the pons produces weakness on the opposite side of the body. “If you injure the pons on the backside, you’re going to have ataxia, which causes problems with coordination of your limbs when you move them,” Harvey said. “There is this sort of tremulous movement pattern.”

Two cranial nerves are supported by structures on top of the pons. One — the sixth cranial nerve — affects eye movement to the side, and the other — the seventh cranial nerve — affects facial movement. A stroke on one side of the pons will affect these nerves causing the eye and facial muscle weakness on the same side of the body as the injury. This stroke also causes weakness on the opposite side of the body.

A stroke affecting both sides of the pons can produce one of the most devastating consequences of brain stem strokes, a condition called locked-in syndrome. In locked-in, all the survivor’s higher cognitive functions are intact, but they can only move their eyes up and down. Harvey explained it in this way: “If injury in one side of the pons causes weakness on the opposite side of the body and facial and eye movement weakness on the same side of the body, then when stroke hits both sides of the pons, you’re going to get weakness on both sides of the body, paralysis on both sides of the face and eye movement problems on both sides. Because the midbrain, which is above the pons, has control over looking up and over opening and closing the eyes, a locked-in patient can do those things when the stroke injures both sides of the pons but not the midbrain.” This type of stroke is rare but can happen as a result of either blood clot or a hemorrhage.

Unlike strokes in areas of the brain that control higher cognitive functions, where there is typically some improvement over time, a complete locked-in syndrome in which all of the fibers that cross the pons are impacted does not typically get better. “These strokes are severe and affect the integrity of the pons very profoundly,” Rabinstein said. “The fibers that cross the pons are destroyed and there is very limited, if any, improvement over time.” However, some patients have an incomplete version of locked-in syndrome where some of these important fibers in the pons are not permanently damaged and can repair. In these cases, recovery is possible, sometimes to the point of achieving independent function again.

Stroke in the Medulla

The medulla is at the base of the brain stem and an injury to one side of it produces weakness on the opposite side of the body. If the stroke affects the area that gives rise to the 12th cranial nerve, which pushes the tongue out, the survivor’s tongue will deviate to the side of the stroke.

A stroke at the top part of the medulla is one of the more common brain stem strokes. “The top part of the medulla is supplied by an artery that comes right off the vertebral arteries,” Harvey said. “The vertebral arteries come together to make the big basilar artery and a lot of atherosclerotic plaques can form there. Clots can lodge in that area and block this little artery coming off that supplies the back side of the medulla.” The result is Wallenberg’s Syndrome: ataxia on the same side of the body that has injury, inability to swallow and a hoarse voice. “You can get vertigo and lose sensation on the side of your face with the injury, and lose pain and temperature sensation on the opposite side of the body.”

Stroke in the medulla also produces Horner’s Syndrome, which affects the sympathetic nervous system. “What happens is the pupil of the eye on the side of the injury gets tiny and you also have a little droop of your eyelid, not a complete paralysis like in the midbrain but a slightly droopy eyelid,” Harvey said.

Other consequences

Some strokes that injure the brain stem can also affect the cerebellum. Recognizing cerebellar strokes is important, especially in the acute phase when swelling can be a problem and may require emergency surgery.

Strokes can disrupt nerve fibers that run through brain stem. “So some of those brain cells in your head are sending information down to the spinal cord. If you injure a nerve fiber tract that is high in the brain stem, it cannot communicate with any other part of the brain stem, the cerebellum or the spinal cord,” Harvey said.

On the other hand, if the cells in your body or spinal cord are sending information up to the brain and that fiber in the brain stem is injured, “then that fiber is done and it’s not going to pass signals on into the brain, and the brain loses important sensory feedback from the body,” Harvey said. “Once injured, the nerve fiber, or axon, will basically shrivel up and disappear. That is called Wallerian degeneration. If you look at an MRI scan, you can sometimes see this tiny pathway of cell death going all the way through the rest of the brain stem where the cell fibers used to pass through and is now filled with fluid because the fibers have died back.”

Recovery

As with other strokes, recovery depends on how severe the injury is. “The typical brain stem stroke is not a massive stroke,” Harvey said. “Although, if you are locked-in, you could call that a massive stroke, although the injury itself is very small. But for the most part, strokes in the brain stem have really nice improvement, just like strokes in the hemispheres do, with proper rehabilitation, of course.”

Brain stem strokes are more likely to produce ataxia. “You don’t get ataxia from cerebral strokes because ataxia only happens when you injure fibers that are in the cerebellum or those passing in or out of the cerebellum to the brain stem,” Harvey said. “Patients with ataxia can often have a prolonged period of poorly coordinated movements, which can have a major impact on their ability to take care of themselves. If the person is just weak like paralysis, it’s pretty much the same recovery as from a cortical injury, regaining motor strength and control.”

The fact that cognition and higher perception are not affected by brain stem strokes is a plus for rehabilitation. One of the major challenges to rehab is the cognitive dysfunction or difficulty with perception that accompanies many strokes. Aphasia also complicates rehab if the survivor cannot understand the therapist’s instructions. “Those are losses of function that make rehabilitation more difficult for the patient and the practitioner trying to help the patient,” Rabinstein said. “That doesn’t happen in brain stem stroke where it is all about the function lost (motor, sensory, coordination, etc.), but there are no problems of understanding or with perception of the deficit.”

Rabinstein shared that, like all strokes these days, brain stem strokes can be treated either with intravenous thrombolysis or with endovascular therapy. These can be life-and function-saving interventions.


Rachel Scanlon Henry

Survivor Rachel Scanlon Henry with son Jason and husband Tim

In April 2003, Rachel S. Henry was a 30-year-old, first-grade teacher in Worcester, Massachusetts. She was in her doctor’s office for a checkup when “my vertebral artery blew,” as she described it, and she had a brain stem stroke. The arterial dissection (a tear, or damage to the inner lining of an artery) was ultimately attributed to a whiplash injury that had happened five years earlier.

She was in the hospital for three weeks, during which she had PT and OT, and “they tried to start speech therapy, but traditional methods were of no use,” she said. Her major deficit was the inability to swallow (severe dysphagia). “I had absolutely no swallow. I couldn’t even swallow my own saliva. For nutrition, I was on a drip for over a week, and then they installed a PEG (Percutaneous Endoscopic Gastrostomy) feeding tube in me. I learned how to manage a suction machine to keep my mouth clear, and the feeding machine.”

Her doctors wanted her stable to begin deep pharyngeal neuromuscular stimulation (DPNS), a type of dysphagia treatment that involves stimulating different points in the throat with a sensor or swab that is frozen. “My speech therapist would jab and tap the sensors in my mouth and throat in a certain sequence,” Rachel said. “A swab can only be used for about 10 seconds. Their goal is to reawaken mechanisms that make you swallow. The goal was to make me gag.”

Because she could not swallow and her only rehab procedure was DPNS, she was discharged to a nursing home — “All the inpatient rehab facilities wanted me to have more than one deficit,” she said. Because of her age and that she only received treatment for one hour a day, the nursing home was not a good fit; she checked herself out the first weekend and never went back.

In about two months, her dysphagia resolved itself, but she had difficulties with her facial muscles. Impaired tongue strength and speaking rate made her speech unclear, but her speech improved. Other deficits continue: “I have no sensation of heat or cold on the entire right side,” she said. “I have no pain sensation on that side. I cannot regulate my body heat, so changes in temperature and humidity are difficult. Extreme weather either way is very difficult.”

She developed spastic muscles on the left side of her face and neck, and her trigeminal nerve, which controls facial and jaw muscles, is spastic. She gets Botox in her facial muscles twice a year. “The injections paralyze the overreacting muscles, which allows me to breathe easier and experience less pain in the head area. Otherwise, at night, the aches and pains can make sleep tough,” she said. “Also I can speak with greater ease after Botox.” Typing is easier than writing longhand, and fatigue is always nearby: “I have exhaustion that comes over me. And I mean exhaustion.” It was years before she overcame the fear of having another stroke.

She returned to teaching about 18 months post-stroke. She was an in-school substitute for a year before she got her own classroom. As an ADA accommodation, she was given an assistant. Fatigue is still a big issue, but she has been back teaching sixth grade for 11 years.

Because of her stroke, her doctor told her she was unlikely to have a baby. Then she got pregnant a month after telling husband Tim that she couldn’t. That was 2008.

“Oops and yippee for us,” she said. Because of the stroke, her pregnancy was considered high risk, and she was transferred to a different hospital in the city. Son “Jason got chylothorax in my belly at about five months. We had to go for 3-D ultrasounds three times a week to see how he was doing. If he wasn’t breathing on any given day, they would have taken him right then,” she said.

After the stroke, she had challenges with edema (swelling), which she controlled by watching her weight. But when she got pregnant, she had to wear compression stockings for several months: “That was like getting a sausage into its casing. Five weeks before the due date, I got wicked bad pre-eclampsia: I was septic, toxic and very sick.” When they were examining her for that, her doctors discovered that she had been having contractions but didn’t know it because her ability to feel pain on the right side is affected. They were able to take baby Jason by C-section. He stayed in the NICU for 12 days; Rachel stayed in the hospital for four days. Both baby and mother did great at home.

She considers the stroke a gift: “If I hadn’t been sent to a high-risk practice because of my stroke, Jason’s chylothorax might have gone undetected,” Rachel said. “And then what, sickness? Death? But thanks to my stroke, we both are here and happy! I credit my stroke with that.”

Editor’s Note: For more of Rachel’s story, visit her blog.


 

Lisha and Michael Norris

Survivor Lisha Norris

When Lisha Norris, 50, of Riverside, California, had a stroke on August 1, 2011, initially it was described to her and husband Michael as minor, but a blood clot to a small area of her brain stem had major consequences — locked-in syndrome.

For weeks in the hospital, the 26-year veteran correctional officer had no movement at all; a tracheotomy allowed her to breathe. One eye was shut. Lisha was in ICU for 60 days and then in an acute rehab for 100 days. Through those efforts she gradually developed very limited movement on the right side of her body, neck, her right index finger and faint movement in her right ankle and toes when given commands from the doctor.

Lisha was discharged for home in January 2012, and Michael, who also worked in the California Department of Corrections, tried to continue working while he took care of his wife of only two years. But after nine months, he retired to be Lisha’s full-time caregiver. Recently, Michael has gotten additional assistance by having a nurse there 24 hours a day, as well as two Certified Nursing Assistants who work part time. “Sometimes I feel like I can’t come up for air because there is always so much to be done,” Michael said.

Lisha cannot speak. When her family communicates with her, they verbally go through the alphabet. When they reach the letter Lisha wants, she blinks her eyes or she may squeeze their hand. “This process can sometimes take a while, but it does work,” said sister Toni Shaw.

Lisha has bladder control and when she needs to be placed on the bedpan, she positions her lips a certain way to let it be known. “The family calls it the ‘stinky lip,’” said Toni. “At bedtime Lisha has a bell placed under her right hand, and she will tap the bell to get Michael’s or the nurse’s attention.”

In the past year, Lisha has been authorized for 18 hours a week of occupational therapy (OT), physical therapy (PT), and speech therapy. In addition, she continues to go to outpatient therapy where she receives electrical stimulation treatments, which have improved her swallowing.

In December 2015, Lisha participated in a clinical study in which she was given a stem cell treatment using adult stem cells by Dr. Steven Cramer at the University of California Irvine. “As a result of this treatment, Lisha gained more control of her upper body and has gradually gotten stronger,” Michael said. “The stem cell treatment allowed her to become stronger in her daily OT, PT and speech therapy. Overall, her endurance, strength, reaction time, response time and awareness have improved.”

Lisha has made many improvements since her time in ICU: Both of her eyes are now open, though her vision is impaired by double vision and limited peripheral vision; she is continent; she breathes on her own; she can move all of her fingers on the right hand, make a fist, has good movement in her right wrist; she can wave, hold a pen and writes her name with limited assistance; she can move her head from side to side and forward and backwards; she can put her tongue out and blow bubbles; she can move her right arm forward and backwards (not a full range of motion); she can shake hands; she can use a mouse to operate a speech computer; she can raise her right leg 45 degrees and hold it for up to 10 seconds; she can wiggle her toes on the right side and move her right ankle. “Five years post-stroke, she is making slight improvements on a monthly basis,” Michael said.

We asked Lisha what she wanted others to know about living with locked-in syndrome. This is what she spelled out in reply: “It is important to know that just because the body is locked-in (paralyzed), the mind remains fully intact. Yes, there are many times when I am depressed and wish I would die. This condition is like being buried alive. I still have all of my emotions, but it is hard to express them. I cry a lot when I am depressed or I hurt from lying in bed too long or think about my children, grandchild, or what lies ahead in the future.”

Toni said the family learned a lot about Lisha’s condition from watching “The Diving Bell and the Butterfly,” a movie about locked-in syndrome.

Michael’s love and devotion are clear. “I try to be strong for Lisha every day, and let her know I am here for her and love her and the family loves her,” he said. “She is in a very dark place in her life. I try to be the best advocate for her. I keep trying to find ways to improve her quality of life — stem cell treatment, acupuncture, full body massages, chiropractor, outpatient therapy and keep open communication with all her doctors. I am by her side every day; I sleep on the couch next to her bed every night. I have only been away from her on a couple of occasions. I eat, breathe and live for taking care of Lisha and trying to find ways to get her back to a normal life — walking and talking. It has been a long, stormy ride.”

This information is provided as a resource to our readers. The tips, products or resources listed or linked to have not been reviewed or endorsed by the American Stroke Association.

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The temporal lobe has several functions, mainly involved with memory, perception and language.

When Stroke Affects the Brain Stem

The brain stem serves as a bridge in the nervous system. It sits at the top of the spinal column in the center of the brain. When a stroke happens there, it can cause a few different deficits and, in the most severe cases, can lead to locked-in syndrome.

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